The rapid spread of the SARS-CoV-2 in the COVID-19 pandemic had raised questions on the route of transmission of this disease. Initial understanding was that transmission originated from respiratory droplets from an infected host to a susceptible host. However, indirect contact transmission of viable virus by fomites and through aerosols has also been suggested. Herein, we report the involvement of fine indoor air particulates with a diameter of ≤ 2.5 µm (PM2.5) as the virus’s transport agent. PM2.5 was collected over four weeks during 48-h measurement intervals in four separate hospital wards containing different infected clusters in a teaching hospital in Kuala Lumpur, Malaysia. Our results indicated the highest SARS-CoV-2 RNA on PM2.5 in the ward with number of occupants. We suggest a link between the virus-laden PM2.5 and the ward’s design. Patients’ symptoms and numbers influence the number of airborne SARS-CoV-2 RNA with PM2.5 in an enclosed environment.

The COVID-19 pandemic has plunged the world into uncharted territory, leaving people feeling helpless in the face of an invisible threat of unknown duration that could adversely impact the national economic growths. According to the World Health Organization (WHO), the SARS-CoV-2 spreads primarily through droplets of saliva or discharge from the mouth or nose when an infected person coughs or sneezes. However, the transmission of the SARS-CoV-2 through aerosols remains unclear. In this study, computational fluid dynamic (CFD) is used to complement the investigation of the SARS-CoV-2 transmission through aerosol. The Lagrangian particle tracking method was used to analyze the dispersion of the exhaled particles from a SARS-CoV-2-positive patient under different exhale activities and different flow rates of chilled (cooling) air supply. Air sampling of the SARS-CoV-2 patient ward was conducted for 48-h measurement intervals to collect the indoor air sample for particulate with diameter less than 2.5 μm. Then, the reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) was conducted to analyze the collected air sample. The simulation demonstrated that the aerosol transmission of the SARS-CoV-2 virus in an enclosed room (such as a hospital ward) is highly possible.

A study was conducted to investigate the antiviral activity of aqueous extracts from Orthosiphon stamineus (OS). Extraction was done using different parts of OS. The whole plant except root (WPOS), leaves (LOS) and flowers (FOS) of OS were extracted using aqueous extraction method. Cytotoxicity was assessed using 3-(4,5-dimethylthiazol-2,5-diphenyl tetrazolium bromide (MTT) assay. Plaque reduction assays were carried out to evaluate the antiviral activity of OS extract against herpes simplex virus type 1 (HSV-1). These include post-treatment, pre-treatment and virucidal assays. High antiviral activity was observed in post-treatment and virucidal assay with 100% reduction of HSV-1 plaque at 0.39 mg/ mL in LOS, FOS and WPOS. In pre-treatment assay, 79%, 84% and 97% plaque reduction using the same concentration was observed in FOS, LOS and WPOS, respectively. In conclusion, this study showed that OS aqueous extract has promising potential to be explored as anti-HSV-1 agent regardless of the mode of treatment.

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The antiviral activity of goniothalamin (GTN) from Goniothalamus umbrosus root, virgin coconut oil (VCO) and aloe vera extract (AVE) have been reported, but the combined activity is yet to be determined. This study aims to determine the stability, cytotoxicity and  effectiveness of pure GTN, combination of GTN and VCO (GTN+VCO) or combination of GTN and AVE (GTN+ AVE) towards in vitro Human Herpesvirus 1 (HHV-1) infection. GTN stability improved significantly (α<0.05) when added with VCO or AVE even though reduction in concentration was noted. The CC50 values for GTN towards vero cells increased when combined with VCO or AVE, which generally reduces the cytotoxicity. Antiviral activity determination by plaque reduction assay in vero cells showed increase in EC50 values with reference to GTN concentration. Selective index (SI) values for pure GTN (11.94),  GTN+VCO (12.23), and GTN+AVE (25.73) respectively. The mode of antiviral activity for all three test substances was post-treatment essentially more effective when treated 2 hours post-infection to cells. The test substances did not protect cells from virus infection if pre-treated and was not virucidal. In conclusion, AVE stabilises GTN in solution and GTN+AVE improves the anti-HHV-1 activity worth for further examination as plant-based antiviral agent.